Mains pressure flusher valve

ABSTRACT

In one embodiment, a mains pressure valve has a body ( 10 ) and a main valve component ( 17 ) which is movable to effect opening and closing of the mains pressure valve. A flow controller ( 36 ) is disposed downstream of the main valve component and has a downstream end. At least one air vent ( 38 ) is provided downstream of the downstream end of the flow controller ( 36 ) and the vent is shielded from the downstream end of the flow controller ( 36 ). In another embodiment, there is a main chamber ( 12 ) within which the main valve component ( 17 ) moves, the main chamber having a control portion ( 40 ). A bypass passageway ( 13 ) has an upstream end ( 35 ) from the control portion ( 40 ) of the main chamber and a downstream end ( 46 ). A control valve ( 42 ) controls the flow through the by-pass passageway ( 13 ) to control the operation of the mains pressure valve. The downstream end ( 46 ) of the bypass passageway ( 13 ) is downstream of the flow controller ( 36 ). In a further embodiment, an upstream portion of the bypass passageway ( 13 ) is defined within a manifold ( 25 ).

FIELD OF THE INVENTION

The invention relates to an improvement to a mains pressure valve for direct connection to a mains pressure water system which, upon activation, will deliver a predetermined volume of water. The invention has particular, but not exclusive, application to flusher valves.

BACKGROUND

This invention relates particularly to valves of the type described in international patent application WO 93/16240. The entire contents of that publication (published on 19 Aug. 1993) are incorporated into this specification by reference.

Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other country.

By way of background, valves of this type are typically used to control the supply of water to a toilet to avoid the need to use header tanks. The valves can be connected directly to the mains pressure network, and can then deliver water directly from a mains pressure network to a toilet, while meeting the necessary safety requirements (eg, preventing any backflow of water into the mains pressure network). Some known valves used to fill this need have required specially adapted plumbing (such as larger diameter pipes, pressure regulators and extra valves) for their proper operation. Such valves have also typically been large and cumbersome and difficult (therefore expensive) to install.

In the valve of patent application WO 93/16240, there is provided a mains pressure valve that includes (a) a main chamber having an inlet for fluid, an outlet for fluid and an upper portion; (b) a non-return valve located downstream of the outlet and adapted to provide resistance to fluid flowing therethrough; (c) a piston located in the main chamber which is movable into and out of sealing engagement with the outlet of the main chamber and having an internal passageway which communicates between the upper portion of the main chamber and the inlet; (d) a port in the upper portion of the main chamber above the piston which permits fluid to flow therethrough; and (e) a control valve associated with the port to regulate the flow of fluid through the port. The same application also discussed such valves further comprising a bypass passageway which communicated between the port in the upper portion of the main chamber and the discharge chamber. Specifically, the bypass passageway typically leads from the control valve (which could be an electronic solenoid-controlled valve, or a manual valve actuator) down beside (at its downstream portion), but separate from, the main chamber and has an outlet just above the upstream end or mouth of the non-return valve. Fluid exiting the bypass passageway's outlet then flows into and through the non-return valve. In particular, when the control valve includes a solenoid-controlled valve, the bypass passageway would typically lead from the solenoid to the top of the valve where it would join the portion integral with the valve which runs down in parallel with the main chamber. By way of example, this passageway is identified by reference numeral 41 in FIG. 1 of PCT/WO93/16240, and the downstream portion by numeral 13 in Numeral 3 of that specification.

Such valves also contain air-vents. The principal purpose of the air vent is to permit entry of air into or adjacent the discharge chamber downstream of the outlet so that water discharged continued to flow away from the valve and was not held by reason of air not being able to enter the downpipe upon flow of the fluid when the valve had recently closed. In the valve discussed in PCT/WO93/16240, the air breaks, or air-vents, are formed by openings in the top of the downpipe, where it abuts an outer surface of the non-return valve. These small gaps are fluidly connected to slots in the outer or flush-pipe nut, which affixes the valve to the top of the downpipe/flush-pipe.

Such valves worked well, but over time some aspects of operation of the valve were seen to be undesirably impaired. In particular, it was observed in some installations that sometimes the full volume of water was not delivered by valves of this type upon actuation. It was found that this could be caused by excessive pressure in the bypass passageway, which could be generated because fluid flowing out through the outlet and into the discharge chamber would not permit fluid to exit from the bypass passageway. As a result, there was increased resistance to the rising of the piston, which therefore continued to more significantly obstruct the passage of fluid from the inlet to the outlet.

Similar problems could also arise where the bypass passageway portion which was external from the valve (for example, on a valve installation where the control valve was controlled by a solenoid—as shown in FIG. 1 of PCT/WO93/16240) was installed incorrectly or partly obstructed.

It was also discovered that when the non-return valve, which was typically made from an elastomeric-type material (such as rubber) aged, fluid discharged from the outlet could leak out through the air vents. This problem was particularly pronounced if there was a significant failure of the non-return valve.

Accordingly, investigations were carried out in an attempt to improve valves of this type and overcome or ameliorate one or more of these limitations to their use.

According to one aspect of the invention, there is provided a mains pressure valve including: (a) a body defining a main chamber having an inlet for fluid, an outlet for fluid and a control portion; (b) a main valve component located in the main chamber which is movable into and out of sealing engagement with the outlet of the main chamber and defining a passageway which provides fluid communication between the inlet and the control portion of the main chamber; (c) a flow controller located downstream of and communicating with the outlet, the flow controller having at least one sidewall and a downstream outlet; (d) a bypass passageway having an upstream end from the control portion of the main chamber and a downstream end; (e) a control valve to control the flow of fluid through the by-pass passageway to control the operation of the mains pressure valve, wherein the downstream end of the bypass passageway is directed towards the at least one sidewall of the flow controller, on the downstream side of the flow controller.

It will be appreciated that, in this context, the entire volume of the pipe downstream of and outside of the flow controller is considered “downstream” there as fluid entering from upstream must flow through the flow controller before it can reach the volume described as “downstream” of the flow controller.

The flow controller may be in the form of a non-return valve. Numerous non-return valves are known in the art. In one embodiment of the invention, the non-return valve is an elastomeric valve having an open mouth at its upstream end leading to converging walls, which meet at its downstream end. Such a valve is known as a duckbill check valve. In the absence of fluid, the converging walls substantially seal the downstream end of the non-return valve to largely prevent fluid flowing from outside the downstream end of the non-return valve into the non-return valve. However, upon pressure of fluid flowing into the mouth of the non-return valve towards its downstream end, the elastomeric converging walls are forced apart, thus creating an opening at the downstream end of the valve for the fluid to exit. As the walls are elastomeric, they can absorb different volumes of fluid flowing through the non-return valve by stretching more where the fluid flow is greater. Further, by reason of fluid in the non-return valve providing the necessary force to open the downstream end of the non-return valve to permit fluid to flow through the non-return valve, the non-return valve provides resistance to fluid flowing through it. This can assist in slowing the closing of the main valve component so that it closes smoothly when the predetermined volume of fluid has passed through the valve. In part, this is achieved by increasing pressure within the valve in the vicinity of the outlet which helps force fluid through the internal passageway into the control portion of the main chamber. However, it will be apparent that other non-return valves can also be used with the invention. Further, the flow controller need not be in the form of a non-return valve or need not be the sole means of performing the non-return function which is the fundamental requirement that fluid downstream of the non-return valve (for example, fluid in the flush-pipe) cannot flow back through the valve and re-enter the mains pressure system (where, for example, it may contaminate drinking water). Other means may be provided which performs or assists with this function.

In one embodiment of the invention, the valve includes a flush pipe nut adaptor which holds the flow controller adjacent the outlet of the valve, and which surrounds the flow controller. The flow controller could, of course, be held in place by any other means known to one skilled in the art. In one embodiment, this flush pipe nut adaptor has one or more openings in it, defining the downstream end of the bypass passageway. Preferably, it also has an external, circumferential, annular recess or groove of greater width than the diameter of the openings, the openings being located within this recess or groove. Accordingly, fluid flowing down the bypass passageway flows to the external recess or groove of the flush pipe nut adaptor, through the openings and ultimately to the pipe which would, in use, be connected for conveying the water downstream of the mains flush valve (eg, to a toilet). In this arrangement, the pressure of any fluid inside (ie, upstream of) the non-return valve has no effect on the pressure of fluid inside the bypass passageway. Surprisingly, it was found that this significantly improved the reliability and consistency of performance of the mains pressure valve.

In a preferred embodiment, at least one vent is provided downstream of the flow controller. These vents may be level with the downstream end of the flow controller. Further, the vents may be shielded from the downstream end of the flow controller. These vents in the form of air vents may be located in the main or flush-pipe nut affixing the downpipe to the valve. To shield the vents from water discharged from the flow controller exiting the downpipe via the vents, the flush pipe nut adaptor has an annular projecting rim from its downstream end which extends past the air-vents. The nut adaptor thus guides fluid discharged from the flow controller past the air-vents and the rim helps avoid “splashes” escaping through the air-vents. Surprisingly, despite the air-vents being lower in the valve assembly, and thus more likely to be exposed to water at higher pressure, reduced leakage was observed. Both the flush pipe nut adaptor and the nut may be made of a hard material, usually metal, preferably an alloy such as brass. The at least one vent also serves as back flow prevention should a negative pressure exist in the body of the valve. On this condition, air will be drawn through the at least one vent thus serving as back-flow prevention. The at least one vent could also be disposed in the downpipe.

Typically, water authorities have standard tests for equipment to be connected to mains pressure systems. Such tests may include applying a negative, or partial vacuum, pressure to the inlet of the valve while there is fluid surrounding the downstream end of the non-return valve to assess whether fluid can be drawn back through the valve. Various standards are set by authorities as to the amount of negative pressure which a valve must be able to withstand in preventing fluid being drawn from the outlet of the valve through the inlet and back into the mains pressure system. A current test involves applying 8 bar of negative pressure to the valve. If the height of water drawn through a ½″ glass tube does not exceed 300 ml then the valve satisfies the test. The present valve satisfies the 300 ml test and also a 30 ml test. For the preferred embodiment valve the amount down through the glass tube is negligible.

In a further preferred embodiment, there is provided a manifold defining an upstream part of the bypass passageway. The manifold incorporates a first port fluidly connected with the control chamber, a passageway from the port to a second port serving as an entrance to the control valve, a third port at an exit of the control valve and a fourth port fluidly connected to a downstream part of the bypass passageway. The downstream part of the bypass passageway may be incorporated into the main valve body. The control valve can then be bolted directly onto the valve at the interface of the second and third ports. In mass manufacture, these two components can be manufactured so that they are predisposed to being fitted together correctly in a manner known to one skilled in the art. This reduces faulty or improper assembly of the valve and control valve in use. Similarly, the outlet from the control-valve can align with the upstream end of the bypass passageway. Preferably, the manifold, the control valve and the body are supplied in fully assembled configuration to preclude wrongful assembly in situ by plumbers.

The area surrounding the flow controller is sometimes referred to as the “discharge chamber”. The discharge chamber is not necessarily a sealed or isolated chamber and the term often defines the general area where fluid exits the valve. Typically, although not necessarily, it is desired that fluid exiting the valve will be carried by a pipe leading away from the valve. For example, in the case of a system for flushing a toilet, water exiting the valve will be carried via a flush-pipe to the toilet itself. The upstream end of the flush-pipe will be connected to the valve, often by a relatively standard-sized fitting which is often called a “flush-pipe nut”. The standard-sizes enable different fittings from different manufacturers, to all be fitted to the one sized flush-pipe. In such a case, particularly where the flow controller projects into the top, or upstream end, of the flush-pipe, the top of the flush-pipe effectively defines the “discharge chamber”.

Suitably, to facilitate connection of the valve with a standard-sized pipe, the flush-pipe nut adaptor is adapted such that it can fit sealingly into the downstream end of the valve adjacent the outlet, and also sealingly engage with the standard-sized flush-pipe or flush-pipe nut so that fluid may flow through the valve and down the flush-pipe without leakage.

It will also be appreciated by one skilled in the art that the valve does not require a down-pipe or flush-pipe to be connected to its downstream end for its useful operation. In some applications, it may be convenient to have the fluid discharged directly from the downstream end of the non-return valve with no further guidance. In such a case, there will not be a flush-pipe nut, and thus air-vents, or air-breaks, would not be necessary.

It will be appreciated also by one skilled in the art that the invention has been described largely in respect of water and for application to a toilet flushing system. However, fluids other than water can be used with the valve as well, and it may be used in applications other than toilet flushing. The invention is not so limited.

The invention may be used with any convenient control valve mechanism. There are many devices known to one skilled in the art for temporarily opening a valve controlling the flow of fluid at low or moderate pressure, the control valve controlling the flow of the fluid through the bypass passageway.

The valve itself is desirably made from a material having sufficient strength, resilience and non-corrosive properties to withstand the pressures involved (which are typically up to 2000 pascals, although the valve can operate with greater pressures). The valve will typically be made from an alloy such as brass. The valve may also desirably be made from rigid polymeric material. The non-return valve and the seals or O-rings are desirably made from elastomeric materials known to those skilled in the art.

In accordance with a second aspect of the invention, there is provided a mains pressure valve having a body; a main valve component which is movable to effect opening and closing of the mains pressure valve; a flow controller downstream of the main valve component, the flow controller having a downstream end; and at least one air vent downstream of the flow controller wherein the at least one vent is shielded from the downstream end of the flow controller.

In accordance with a third aspect of the invention, there is provided a mains pressure valve including: (a) a body defining a main chamber having an inlet for fluid, an outlet for fluid and a control portion; (b) a main valve component located in the main chamber which is movable into and out of sealing engagement with the outlet of the main chamber and defining a passageway which provides fluid communication between the inlet and the control portion of the main chamber; (c) a bypass passageway having an upstream end from the control portion of the main chamber and a downstream end which is downstream of the outlet of the main chamber, the bypass passageway having a downstream portion which is incorporated into the main body and an upstream portion; (d) a control valve to control the flow through the by-pass passageway to control the operation of the mains pressure valve; (e) a manifold connectable to the body, the manifold defining the upstream portion of the bypass passageway including a first port fluidly connected with the control portion and a second port fluidly connected to the downstream portion of the bypass passageway.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

It will also be understood that the term “comprises” (or its grammatical variants) as used in this specification is equivalent to the term “includes” and should not be taken as excluding the presence of other elements or features.

DESCRIPTION OF THE DRAWINGS

The invention will now be further illustrated with reference to the accompanying drawings in which:

FIG. 1 is a cross-section of a valve according to the invention;

FIG. 2 is a perspective view of the bonnet portion of the embodiment of FIG. 1;

FIG. 3 is a cross-section of the bonnet normal (ie, horizontally) to the cross-section shown in FIG. 1.

FIGS. 4 to 8 are engineering cross-section drawings of specific components of one embodiment of the invention as shown in FIG. 1. FIG. 4 is flow valve housing 54 (and channel 23 can more clearly be seen). FIG. 5 is adaptor 50 (also showing openings 60). FIG. 6 is piston 17 and FIG. 7 is flush-pipe nut 53.

In the drawings illustrating various embodiments of the invention, for convenience only, like components are given the same numerical reference.

FIG. 1 shows a valve having a valve body 10 comprising principally an inlet 11, a main chamber 12, a bypass passageway 13, an outlet 15 and a discharge chamber 14, defined by flush-pipe adaptor 50 and downstream by flush-pipe nut 53. Adaptor 50 has two threads 51 and 52. Inner thread 51 engages with a corresponding thread in valve body 10 and outer thread 52 engages with the top of the flush-pipe nut 53. A discharge pipe (not shown) fits to the bottom of flush-pipe nut 53 in a manner known in the art.

The main chamber 12 contains a main valve component in the form of a piston 17. The piston 17 has in its lower portion a depending foot 45, having an annular groove 16 in which is located a seal 18 which engages with a corresponding seat at outlet 15 formed in the valve body 10 to form a seal when piston 17 is in the closed position. This prevents water flowing from inlet 11 to discharge chamber 14. Depending foot 45, of slightly smaller diameter than the discharge chamber 14, forms a choke on piston 17.

Piston 17 also has a transverse passageway 19 and an axial passageway 20 which communicate with one another. A flow valve housing 54 screws into axial passageway 20 and rests on seal 55. A filter 21 is mounted at the upstream end of housing 54, at one end of the axial passageway 20 where it meets with the transverse passageway 19. A small flow valve 22 is located in housing 54 downstream of the filter. Fluid flowing through flow valve 22 can then pass through channel 23 in the housing 54 to a control portion 40 of the main chamber 12. Channel 23 is offset from the main axis of the valve so that it is not blocked by spindle 30 when the valve is open. Seal 56 restricts leakage from control portion 40 around piston 17.

Water initially flows from the inlet 11 into main chamber 12 and into transverse passageway 19. Thereafter a portion of the water flows into the axial passageway through flow valve 22, and through channel 23 into the control portion 40. The flow valve regulates the rate of water permitted to flow through channel 23 into control portion 40.

Situated above main chamber 12 is a manifold 25 (also shown in FIGS. 2 and 3) which contains a spindle 30 which projects into the main chamber 12. Manifold 25 is partially located in the main chamber 12. The amount of the spindle projecting into the control portion 40 may be adjusted by means of a bolt head 33. To restrict leakage of water from the manifold 25, an “O”-ring 24 is located above main chamber 12. Seal 59 restricts leakage where the bypass passageway 13 connects from manifold 25 to valve body 10. The spindle 30 projecting into the main chamber 12 controls the extent of upward movement of piston 17 and the volume of control portion 40 when the valve is in the open position. That volume controls the period between actuation of the valve and the cessation of water flow through the valve.

A bypass passageway 13 flows from the upper portion 40 through the manifold 25 forming an upstream portion of the bypass passageway. The bypass passageway continues in a downstream portion in the form of a conduit defined in valve body 10.

In the upstream portion of the bypass passageway, the manifold 25 has a port 35 leading from the upper portion 40. A control valve 42 is connected to the port 35 via a first passageway 41 (see FIGS. 2 and 3). Valve 42 is controlled by a solenoid (in the embodiment shown) which is electrically actuated to open valve 42 for a predetermined period or time or times and then close. Manifold 25 has a mouth 57 or “connecting opening” (see FIG. 2) in which is located both the downstream end of a first passageway 41 and the upstream end of a second passageway 43 leading away from valve 42. The downstream end of the second passageway connects to the downstream portion of the bypass passageway. The downstream end 46 of bypass passageway 13 is adjacent the mouth 47 (inlet) of, but outside, the flow controller in the form of a duckbill valve 36.

An “O”-ring 37 assists in avoiding any leak from the discharge chamber 14 by forming a seal between adaptor 50 and valve body 10. Duckbill valve 36 (having mouth 47 and downstream end 48) is immediately downstream of outlet 15.

When the valve is in the closed position, inlet 11 and main chamber 12 are filled with water. In this state, the total force exerted on the top of the piston 17 by the water contained in the control portion 40 of the main chamber 12 is greater than the force exerted by the water in the lower portion of the main chamber 12 because the piston 17 has greater surface area exposed to the control portion 40. In this state, the valve is closed because seal 18 prevents water flowing from inlet 11 to discharge chamber 14.

Upon actuation of the control valve 42, water is permitted to flow from control portion 40 through bypass passageway 13 and into discharge chamber 14. Consequently, the force of the water on the top of piston 17 in the control portion 40 of the main chamber becomes less than the force exerted by the water in the lower portion on the base of piston 17. This causes piston 17 to rise and permits water to flow from inlet 11 through the duckbill valve 36. Water discharged from passageway 13 into discharge chamber 14 flows, and is drawn (in part by a venturi effect by the water flowing from the inlet 11 to discharge chamber 14), down to discharge chamber 14 via passageway 13 to its downstream end 46 through openings 60 in adaptor 50 to discharge chamber 14. The duckbill valve 36 provides some resistance to the water flowing into discharge chamber 14 which reduces any vacuum force created by the flowing of water through the outlet which may otherwise cause piston 17, at normal operating (mains) pressures, to be prematurely drawn down, closing the valve prior to the action of the closing mechanism explained below. Further, since the duckbill valve is constructed of flexible and elastic material, it can provide an appropriate degree of resistance over a range of water flow-rates and pressures experienced at outlet 15. In this state, water from inlet 11 will still flow into channel 19, through filter 20, through flow valve 22 and then through channel 23 into control portion 40.

Upon release of the control valve 42 (which in normal use would be very shortly after actuation), water is no longer able to pass through from control portion 40 to passageway 13. Thus, water flowing through piston 17 into upper portion 40 will force piston 17 back down to its initial position in the “closed” state. As seal 18 nears its seat at outlet 15 in main body 10, the flow of water from inlet 11 to discharge chamber 14 will slowly decrease. Duckbill valve 36 maintains some resistance to the water being discharged by elastically contracting due to the lower flow-rate (and thus lower pressure inside the duckbill valve).

The flow of water though the valve stops upon seal 18 again forming a seal with its corresponding seat in main body 10 preventing the flow of water from inlet 11 to discharge chamber 14. Air-vent 38 in flush pipe nut 53 will enable any remaining water in discharge chamber 14 to drain away by allowing air to enter from outside the valve/nut assembly into the discharge chamber. This creates an air-break between the valve and the flush-pipe. Depending rim 58 from adaptor nut 50 helps avoid fluid (being discharged through duckbill valve 36) from splashing out through air-vents 38.

The means for actuating the valve may be selected to provide alternate flushing options. For example appropriate electronic control for the valve 42 may permit selection of different volumes of water to be discharged. Such electronic controls are well known. Manual actuators are also used and known. 

1. A mains pressure valve having a body; a main valve component which is movable to effect opening and closing of the mains pressure valve; a flow controller downstream of the main valve component, the flow controller having a downstream end; and at least one air vent downstream of the flow controller wherein the at least one vent is shielded from the downstream end of the flow controller.
 2. The mains pressure valve as claimed in claim 1 further comprising an adapter nut surrounding the flow controller wherein the adapter nut incorporates a dependent annular rim to shield the at least one vent from the downstream end of the flow controller.
 3. The mains pressure valve as claimed in claim 2 wherein the at least one vent is provided in a further nut threadingly engageable with the adapter nut.
 4. The mains pressure valve as claimed in claim 3 wherein the further nut is in the form of a flush pipe nut adapted to connect to a flush pipe.
 5. The mains pressure valve as claimed in claim 1 wherein the at least one vent is disposed level with the downstream end of the flow controller.
 6. The mains pressure valve as claimed in claim 1 wherein the flow controller comprises an elastomeric duckbill valve.
 7. The mains pressure valve as claimed in any one of the preceding claims claim 2 wherein the flow controller has an open mouth at an upstream end leading to converging walls which meet at the downstream end, the open mouth surrounded by a flange and the adapter nut operating to clamp the flange to the body of the mains pressure valve.
 8. A mains pressure valve including: (a) a body defining a main chamber having an inlet for fluid, an outlet for fluid and a control portion; (b) a main valve component located in the main chamber which is movable into and out of sealing engagement with the outlet of the main chamber and defining a passageway which provides fluid communication between the inlet and the control portion of the main chamber; (c) a flow controller located downstream of and communicating with the outlet, the flow controller having at least one sidewall and a downstream outlet; (d) a bypass passageway having an upstream end from the control portion of the main chamber and a downstream end; (e) a control valve to control the flow through the by-pass passageway to control the operation of the mains pressure valve, wherein the downstream end of the bypass passageway is directed towards the at least one sidewall of the flow controller, on the downstream side of the flow controller.
 9. The mains pressure valve as claimed in claim 8 wherein the flow controller is an elastomeric duckbill valve.
 10. The mains pressure valve as claimed in claim 8 wherein an adapter nut surrounds the non-return valve and the adapter nut is provided with openings extending therethrough which comprise the downstream end of the bypass passageway.
 11. The mains pressure valve as claimed in claim 10 wherein a recessed portion is provided in the external periphery of the adapter nut and the openings are disposed in the recessed portion.
 12. The mains pressure valve as claimed in claim 10 wherein the flow controller has an open mouth at its upstream end with the at least one sidewall converging to meet at its downstream end, the open mouth surrounded by a flange and the adapter nut operating to clamp the flange to the body of the mains pressure valve.
 13. The mains pressure valve as claimed in claim 10 wherein at least one vent is provided, downstream of the flow controller.
 14. The mains pressure valve as claimed in claim 13 wherein the at least one vent is shielded from the downstream end of the flow controller.
 15. The mains pressure valve as claimed in claim 14 wherein the adapter nut incorporates a dependent annular rim to shield the at least one vent from the downstream end of the flow controller.
 16. The mains pressure valve as claimed in claim 13 wherein the at least one vent is disposed level with the downstream end of the flow controller.
 17. The mains pressure valve as claimed in claim 13 wherein the at least one vent is provided in a further nut threadingly engageable with the adapter nut.
 18. The mains pressure valve as claimed in claim 17 wherein the further nut is in the form of a flush pipe nut adapted to connect to a pipe.
 19. The mains pressure valve as claimed in claim 8 wherein the main valve component is a piston and the passageway providing fluid communication between the inlet and the control portion of the main chamber is an internal passageway of the piston.
 20. The mains pressure valve as claimed in claim 8 wherein the bypass passageway includes an upstream portion and a downstream portion, the downstream portion being incorporated into the body, there being further provided, a manifold connected to the body, the manifold defining the upstream portion of the bypass passageway including a first port fluidly connected with the control portion and a second port fluidly connected with the downstream portion of the bypass passageway.
 21. The mains pressure valve as claimed in claim 20 wherein the manifold further comprises a control valve inlet and a control valve outlet.
 22. The mains pressure valve as claimed in claim 21 wherein the control valve inlet and a control valve outlet are disposed on a same side of the manifold.
 23. The mains pressure valve as claimed in claim 22 wherein the control valve is connected to said side of the manifold.
 24. The mains pressure valve as claimed in claim 20 wherein the manifold comprises a moulded plastics body.
 25. A mains pressure valve including: (a) a body defining a main chamber having an inlet for fluid, an outlet for fluid and a control portion; (b) a main valve component located in the main chamber which is movable into and out of sealing engagement with the outlet of the main chamber and defining a passageway which provides fluid communication between the inlet and the control portion of the main chamber; (c) a bypass passageway having an upstream end from the control portion of the main chamber and a downstream end which is downstream of the outlet of the main chamber, the bypass passageway having a downstream portion which is incorporated into the main body and an upstream portion; (d) a control valve to control the flow through the by-pass passageway to control the operation of the mains pressure valve; (e) a manifold connectable to the body, the manifold defining the upstream portion of the bypass passageway including a first port fluidly connected with the control portion and a second port fluidly connected with the downstream portion of the bypass passageway.
 26. The mains pressure valve as claimed in claim 25 wherein the manifold further comprises a control valve inlet and a control valve outlet.
 27. The mains pressure valve as claimed in claim 26 wherein the control valve inlet and a control valve outlet are disposed on a same side of the manifold.
 28. The mains pressure valve as claimed in claim 27 wherein the control valve is connectable to said side of the manifold.
 29. The mains pressure valve as claimed in claim 25 wherein the manifold comprises a moulded plastics body.
 30. The mains pressure valve as claimed in claim 25 wherein the mains pressure valve is provided 